Currently it should work with Json-RPC 2.0 back ends. Examples which also show the correct responses are included.

Help is welcome! So if you can contribute just contact me on the project page on google code above. E.g. Json-RPC 1.0 support will be welcome. Feedback, testing, functionality, bugs, bug fixes, ...

Isomorphic - if you can use the code - feel free! The license should also allow you to include the code into your commercial offerings. But - IANAL.

Status: This is alpha code. I do not recommend to use it on a production server.
It works for me but no guarantees.
It certainly lacks tests and functionality. And - well - I am certainly not an experienced JavaScript or SmartClient coder.
If SmartClient offers a Json-RPC data source in the future I guess this little project will not be continued.

License: LGPL as SmartClient. But the code currently includes portions of SmartClient LGPL code, a public domain library and a BSD licensed library.